repellente

Repellente is a term used in several Romance languages (Italian, Spanish, Portuguese) to denote an agent or substance that drives away or discourages the approach of organisms, materials, or forces. Its root derives from the Latin repellere, meaning "to drive back." In common usage it most often refers to products that prevent insects, animals or moisture from contacting people, crops, structures or stored goods.

Types of repellents include insect repellents (topical or spatial formulations), mammal and bird repellents (chemical, visual or auditory deterrents), and water- or stain-repellent coatings for textiles and building materials. Insect repellents may be synthetic (DEET, picaridin, IR3535) or plant-derived (oil of lemon eucalyptus, citronella), and are designed to reduce biting or landing rather than to kill. Physical repellents include barriers, clothing treatments and bed nets.

Mechanisms of action vary: olfactory masking or irritation, taste aversion, sensory overstimulation, or creating an unfavorable physical surface. Uses range from public-health protection against vector-borne disease to agricultural crop protection and preservation of property.

Regulation and safety differ by jurisdiction; approved products are evaluated for human toxicity, environmental impact and efficacy. Concerns can include skin irritation, effects on non-target species and aquatic toxicity. Ongoing research seeks longer-lasting, safer formulations and non-chemical alternatives such as pheromone disruption, biological controls and improved materials technology. Effectiveness depends on formulation, correct use and the target species.